The present invention relates to a compact electronic component and a semiconductor device whose final formed package size is close to the size of the chip (semiconductor element), to methods of manufacturing these, to a circuit board on which these are mounted, and to an electronic instrument having this circuit board.
To pursue high density mounting in semiconductor devices, bare chip mounting is the ideal. However, quality control and handling of bare chips are difficult. Far this reason, CSP (chip size/scale package) technology, in which the package size is close to the chip size, has been developed.
In such a CSP semiconductor device, an important problem is to relieve the thermal stress due to the differences in coefficient of thermal expansion between the semiconductor chip and the mounting board. In particular, as the number of pins continues to increase, it is essential that no-wiring breaks are caused by thermal stress, since wiring is required to connect from the electrodes to the solder balls.
The present invention addresses the above described problems, and has as its object the provision of an electronic component, a semiconductor device, methods of manufacturing these, a circuit board on which these are mounted, and an electronic instrument having this circuit-board.
The semiconductor device of the present invention comprises a semiconductor element, an external electrode provided within the region of the semiconductor element for external connection, wiring connected through a connection portion to the external electrode and electrically connecting the semiconductor element and the external electrode, a stress relieving portion provided on the semiconductor element, and a stress transmission portion transmitting stress from the external electrode to the stress relieving portion.
Since the semiconductor element and external electrode of the present invention are connected by the wiring, the pitch of external electrode can be converted as required. The stress transmission portion transmits stress from the external electrode to the stress relieving portion, and stress can be thus relieved.
The wiring is connected to the external electrode through a connection portion. The connection portion is not restricted to the case of existing as a separate member between the wiring and the external electrode, but includes the case of being a part of at least one of the wiring and external electrode. The connection portion is not restricted to directly contacting at least one of the wiring and external electrode, but includes the case of not directly contacting either. That is to say, the connection portion of the present invention indicates at least a part of the member electrically connecting the wiring and external electrode.
More specifically, the wiring may be provided on the stress relieving portion, and the stress transmission portion may be Provided in the connection portion.
By this means, since the wiring is provided on the stress relieving portion, the connection portion and stress transmission portion are provided on the stress relieving portion, and the stress from the external electrode is transmitted to the stress relieving portion.
Alternatively, the wiring may be provided under the stress relieving portion, the connection portion may be provided to pass through the stress relieving portion, and the stress transmission portion may be formed on the stress relieving portion integrally with the connection portion,
By this means, since the connection portion passes through the stress relieving portion, the connection portion does not transmit stress vertically to the stress relieving portion. In place of this, the stress transmission portion provided on the stress relieving portion transmits stress to the stress relieving portion.
The stress relieving portion may be formed with a thickness to reach the stress transmission portion from the wiring.
The stress relieving portion may have a groove formed outside of the stress transmission portion. By forming a groove, the stress relieving portion is more easily deformed, and stress from the stress transmission portion can be absorbed more easily.
The stress relieving portion may have a space formed between a contact position on the wiring and a contact position under the stress transmission portion. By this means, the stress relieving portion is more easily able to deform, and stress from the stress transmission portion can be absorbed more easily.
A stress relieving portion having such a space may be formed with a thickness to reach the stress transmission portion from the wiring, and then may be etched from the outside of the stress transmission portion to underneath thereof.
The present invention may further comprise a supplementary transmission portion provided at least between a root periphery of the external electrode and the stress relieving portion, and transmitting stress from the external electrode to the stress relieving portion.
By means of the supplementary transmission portion, stress from the external electrode is transmitted to the stress relieving portion, and a concentration of stress between the external electrode and the stress transmission portion can be prevented.
The supplementary transmission portion may be formed of a material capable of being used for the stress relieving portion.
The stress relieving portion may include a first stress relieving layer and a second stress relieving layer formed on the first stress relieving layer;
the wiring may be provided between the first and second stress relieving layers,
the connection portion may be provided to penetrate the second stress relieving layer; and
the stress transmission portion may be formed on the second stress relieving layer integrally with the connection portion.
By this means, the connection portion transmits stress in the vertical direction to the first stress relieving layer. Meanwhile, the stress transmission portion transmits stress to the second stress relieving layer. In this way, stress is relieved at two locations.
The stress relieving portion may include a first stress relieving layer and a second stress relieving layer formed on the first stress relieving layer;
the wiring may be provided between the first and second stress relieving layers;
the connection portion may be provided to penetrate the second stress relieving layer; and
the stress transmission portion may include a first transmission portion formed between the first and second stress relieving layers integrally with the connection portions and a second transmission portion formed on the second stress relieving layer integrally with the connection portion.
The connection portion transmits stress in the vertical direction to the first stress relieving layer. Stress is also transmitted to the first stress relieving layer from the first transmission portion of the stress transmission portion. Furthermore, the stress transmission portion has a second stress transmission portion, and this second stress transmission portion transmits stress to the second stress relieving layer. In this way, stress is relieved at three locations.
It is preferable that the second transmission portion has a larger area than the first transmission portion, and transmits the stress to the second stress relieving layer.
Since the second transmission portion transmits a large amount of stress, the stress transmitted by the first transmission portion is comparatively small. The first transmission portion is close to the direct contact portion of the connection portion and wiring. Therefore, by reducing the stress transmitted from the first transmission portion, the effect on this contact portion can be reduced.
It is preferable that the stress transmission portion is provided without contacting the connection portion.
By this means, the stress transmission portion does not transfer stress to the direct contact portion of the connection portion and wiring.
The stress relieving portion may have an isolation portion for inhibiting transmission of the stress between a support region supporting the stress transmission portion and a connection region in which the connection portion is formed.
Because the isolation portion is provided, stress transmitted from the stress transmission portion to the support region of the stress relieving portion is not transmitted to the connection region. Therefore, transfer of stress from the stress transmission portion through the stress relieving portion to the connection portion also does not occur.
Here, the isolation portion may for example be a groove.
The wiring preferably has a bent portion forming an empty portion with the semiconductor element.
By this means, since the wiring can freely deform in the bent portion, maximum stress absorption is possible.
A gel material may be injected in the empty portion to protect the bent portion.
The stress relieving portion may include a first stress relieving layer and a second stress relieving layer formed on the first stress relieving layer;
the wiring may include a first wiring portion formed below the first stress relieving layer and a second wiring portion formed between the first and second stress relieving layers;
the connection portion may include a first wiring connection portion penetrating the first stress relieving layer and connecting the first and second wiring portions and a second wiring connection portion penetrating the second stress relieving layer and connecting the external electrode and the second wiring portion;
the first and second wiring connection portions may be disposed on different planes; and
the stress transmission portion may include a first transmission portion formed between the first and second stress relieving layers integrally with the first wiring connection portion, and a second transmission portion formed on the second stress relieving layer integrally with the second wiring connection portion.
Since the first and second wiring connection portions of the present invention are provided with first and second transmission portions respectively, in each of the wiring connection portions, stress can be transmitted to the stress relieving layer. The contact position of the first wiring connection portion with respect to the first and second wiring portions, and the contact position of the second wiring connection portion with respect to the external electrode and second wiring portion are disposed on different planes. Therefore, stress applied to one of the contact positions is not directly easily transferred to the other contact position. Since stress transferred from the external electrode is relieved before reaching the semiconductor element, the effect on this semiconductor element can be reduced.
The wiring may be brought out from the external electrode substantially at right angles to a direction of generation of the stress.
By this means, the generating direction of the stress and the extending direction of the wiring are substantially orthogonal. Thus the application of tension to the wiring in the direction of its extension and consequent wiring breaks can be prevented.
The stress transmission portion may be formed at a position outside of the connection portion.
Since the stress transmission portion is transmitting stress at a peripheral position of the connection portion of the external electrode and wiring, stress can be transmitted over a large area.
The electronic component of the present invention comprises an electronic element; an external electrode for external connection; wiring electrically connecting the electronic element and the external electrode; a stress relieving portion provided on the electronic element; and a stress transmission portion transmitting stress from the external electrode to the stress relieving portion, at a peripheral Position of an electrical connection portion of the external electrode and the wiring.
The method of manufacturing an electronic component of the present invention comprises:
a step of integrally forming in substrate form a plurality of electronic element;
a step of forming an electrode on the electronic element in substrate form;
a step of providing a stress relieving portion on the electronic element in substrate form, avoiding the electrode;
a step of forming wiring from the electrode;
a step of providing a stress transmission portion transmitting stress from the external electrode to the stress relieving portion, in a peripheral position of the electrical connection portion of the wiring and external electrode; and
a step of separating the electronic element in substrate form into individual elements.
The method of manufacturing a semiconductor device of the present invention comprises:
a step of forming an electrode on a wafer;
a step of providing a stress relieving portion on the wafer avoiding the electrode;
a step of forming wiring from the electrode;
a step of providing a stress transmission portion transmitting stress from the external electrode to the stress relieving portion, in a peripheral position of the electrical connection portion of the wiring and external electrode; and
a step of separating the wafer into individual elements.
With an aspect of the present invention, after a stress relieving layer, wiring, and external electrode are formed on the wafer, the wafer is cut up to obtain individual semiconductor devices. Therefore, since the formation of stress relieving layer, wiring, and external electrode can be carried out simultaneously for a large number of semiconductor devices, the fabrication process can be simplified.
The step of forming a stress relieving portion may be carried out after the step of forming wiring; and
a step of forming a groove by etching in the stress relieving portion outside of the stress transmission portion may be performed before the step of separating the wafer.
By forming the groove, the stress relieving portion is more easily deformed, and stress from the stress transmission portion can be absorbed more easily.
The step of forming the stress relieving portion may be carried out after the step of forming wiring; and
a step of etching the stress relieving portion to under the stress transmission portion may be performed before the step of separating the wafer.
By this means, the stress relieving portion has a space formed between a contact position over the wiring and a contact position under the stress transmission portion. Thus, the stress relieving portion is more easily deformed, and stress from the stress transmission portion can be absorbed more easily.
A step of providing a material capable of being used for the stress receiving portion from over the stress relieving portion to at least a root periphery of the external electrode, to form a supplementary transmission portion, may be performed before the step of separating the wafer.
In this way, when the supplementary transmission portion is formed, stress from the external electrode is transmitted to the stress relieving portion by means of the supplementary transmission portion, and a concentration of stress between the external electrode and the stress transmission portion can be prevented.
The circuit board of present invention has the above described semiconductor device and a substrate on which a desired wiring pattern is formed; and external electrodes of the semiconductor device are connected to the wiring pattern. The electronic instrument of the present invention has this circuit board.